The biggest problem can be the smallest thing, and that's the case in the sewer world.

More than 20 million gallons of raw sewage spilled into California waterways last year, according to the state Department of Water Resources Control Board. That's not counting the partially treated sewage that makes its way into our water from overflows and sewer system malfunctions.

Many big sewer pipes are old, and many of the sewage treatment plants are antiquated. But the biggest problem faced by sewer systems in California is the tiny pipe called the lateral.

That's the pipe that runs from your home to the street, the small pipes under all of our homes that end up joining the bigger sewer pipes. When those pipes develop cracks, water leaks into them.

Storm water itself would not overwhelm a sewage system, because it's designed to be a closed system. Storm water is not supposed to BE in sewer pipes. So in one way, it shouldn't even matter what the weather is like – storm water shouldn't really mix with sewage at all.

But during a rainstorm, water seeps into your broken lateral pipe, and all your neighbors' pipes, and that rainwater mixes with sewage in the sewer pipes, and the volume of water/sewage can actually build up far beyond the capacity of the sewer pipe. And in the same way, thousands and thousands of gallons of water mixed in with the sewage can swamp a treatment plant during a rainstorm.

That's the number one concern of sewage treatment plants now. And the sewer districts need your help.

Those laterals are owned by homeowners. They're on private land, so the district can't just go in there and tear them up to replace or fix them.

However, most sewer districts offer a service where they will inspect your laterals to check for leaks, and many have started programs where the district will help pay the cost of repairing or replacing those pipes.

Sewer systems are run by local municipalities. Most communities have a local sewer district, and officials at the district can help you inspect and fix your lateral pipes.

Listen to the Sewage Spills Increasing radio report online.

Unless our sewage happens to end up in the Bay and in the headlines, most of us probably never give a second thought to where our wastewater is headed each time we run the tap or flush the toilet.

To learn more about the travels of sewage, I took a tour of the Las Gallinas Valley Sanitary District treatment plant led by Plant Manager Matt Pierce. The plant has been in operation for about 50 years and serves over 30,000 residents in north San Rafael.

After leaving sinks and showers throughout the District, wastewater travels through a network of pipes and pump stations. Once the sewage arrives at Las Gallinas, it passes through an inlet screen and a grit chamber, which together remove much of the dense, inorganic material-"like diamond rings," Matt jokes.

A lot of what happens at the plant is not that different from what happens in your compost pile: "It's basically bacteria at work," Matt points out. (The much bigger challenge for sanitation districts these days are all the unnatural things we're putting down the drain: household chemicals, personal care products, pharmaceuticals.)

From the grit chamber the sewage heads into a series of clarifiers, where gravity causes the organic solids to settle out. The biosolids pass through a thickener and then an anaerobic digester-the most, ahem, aromatic stop on our tour. After further thickening in storage ponds, the sludge is injected into a disposal field.

Meanwhile, the liquid from the clarifiers travels through two biofilters, where rotating arms spray the water over rock beds. The organic matter in the wastewater is a feast for microbial slime living on the rocks. In the nitrification tower, more microorganisms break down the ammonia in the water. In the final stages of treatment, the wastewater is chlorinated to kill any remaining bacteria, then dechlorinated since the chlorine is toxic to many aquatic species. Finally, the treated water is sprayed onto District fields or discharged into Miller Creek where it flows to San Pablo Bay.

The District has done a lot to minimize the environmental impacts of its operations. The plant is powered by a field of solar panels. The methane released in the sludge treatment process is captured and used to generate power and heat the digester. Some of the treated wastewater supports acres of fresh and saltwater wetlands-in fact the District's land is a favorite local gem for walkers and birders. And in a partnership with the Marin Municipal Water District, more than a million gallons of treated wastewater are recycled daily for landscape irrigation and other projects.

There are plans to make even fuller use of the reclaimed water. The Bay Institute-in partnership with the Sonoma County Water Agency, Las Gallinas, and three other North Bay sanitation agencies-has developed a plan to use recycled water for wetland and creek restoration and for agricultural irrigation. Legislation sponsored by Congressman Mike Thompson to establish the program passed the House late last year; Senator Dianne Feinstein has introduced similar legislation that we are hopeful will pass this year.

With California's growing demands for water, such creative means to conserve and recycle are critical to helping prevent this precious resource from just going "down the drain."


Ann Dickinson is Communications Manager for The Bay Institute (www.bay.org), a nonprofit research, education, and advocacy organization dedicated to protecting and restoring San Francisco Bay and its watershed, "from the Sierra to the sea."